Strontium (M) abscorbate compositions containing same, method for making same and method of using same

ABSTRACT

A compound of formula (ascorbate) 2 Sr:(M +a ) x (ascorbate) y , or ascorbate) 2 Sr:Ca(ascorbate) 2 , a composition containing the same, a method of making the same and a method of administering the same as a supplement.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a non-provisional U.S. utility patent application claiming priority to provisional U.S. application No. 60/935,216 filed before the U.S. Patent and Trademark Office (USPTO) on Aug. 1, 2007. The entire contents of provisional U.S. application No. 60/935,216 are incorporated herein by reference including its specification, claims, abstract and drawing figures for all purposes.

This application also incorporates by reference the entirety of U.S. utility patent application Ser. No. 12/155,325 filed before the USPTO on Jun. 2, 2008. U.S. utility patent application Ser. No. 12/155,325 is a non-provisional application of provisional application No. 60/924,860 which provisional application was filed on Jun. 1, 2007 before the USPTO. The entire contents of U.S. non-provisional application Ser. No. 12/155,325 and the entire contents of U.S. provisional application No. 60/924,860 are incorporated by reference herein.

BACKGROUND

1. Field

The presently claimed invention is directed to strontium (M) ascorbate compound(s), compositions containing the same, method(s) for making the same and method of using the same. More particularly, for example, strontium (M) ascorbate may be used as a dietary supplement. As a further example, the dietary supplement may be used to administer an increased level of ascorbate to a subject in need thereof and/or to a subject to provide ascorbate as a dietary supplement.

2. Description of the Related Art

The nutritional value of ascorbic acid (vitamin C) is well known and its benefits have long been established. Most animals have a liver enzyme, which enables them to manufacture vitamin C in situ, by conversion of sugar into ascorbic acid. However, humans do not have this enzyme. Furthermore, humans are incapable of storing vitamin C, partly because it is metabolized and secreted and partly because it is a water-soluble vitamin.

Because humans lack the biochemical mechanism to produce vitamin C, it has to be obtained through food and/or nutritional dietary supplementation. Vitamin C is found in many fruits and vegetables, but it can also be supplemented into a number of dietary products including food, beverages, and dietary supplements.

Vitamin C has been implicated in more than 300 biological processes. The more important roles include the co-reaction with enzymes in the formation of collagen, the anti-scorbutric effect, the antioxidant and free radical scavenging reactions, energy metabolism accentuation in polynuclear leukosites and facilitation of iron absorption, among others.

The importance of vitamin C has been elucidated through understanding health complications which arise when vitamin C levels are deficient. Vitamin C deficiency can lead to a variety of conditions such as abnormal bleeding of the skin, mucous membranes, internal organs and muscles (due to impaired capillary integrity), hemorrhages, edema, joint pain, anorexia, and impaired wound healing (Mahan, L. K. and Arlin, M. T. Therapy 8^(th) edition Philadelphia W. B. Saunders; Anderson, W. A. D. 1971 and Pathology 6^(th) edition St. Louis, The C. V. Mosby Company).

Conversely, it has been shown that Vitamin C is well tolerated by humans and can safely be taken in mega-doses as noted by the nobel laureate Linus Pauling (J. S. Roe, Standard Method of Clinical Chemistry, edited by Seligson D. New York, Academic Press, 1961, Vo. 3, p. 35).

Clinical studies suggest that ascorbic acid participates in hydroxylation reactions associated with cholesterol metabolism (Ginter, E. “Cholesterol: Viamin C controls its Transformation to Bile Acids” Science 1973, 179:702-704). Humans can convert cholesterol into bile acids through a series of biochemical reactions. This allows the body to rid itself of excess cholesterol. Another more notable benefit of vitamin C is the formation of protocollagen through hydroxylation of proline and lysine. The enzyme hydroxylase forms the bonds with proline and collagen uses ascorbic acid as the reductant.

Strontium is a group (IIA) element similar in many ways to calcium, the most obvious being they are both divalent cations. Because strontium is a divalent cation, like calcium, without being bound by theory, it is thought that strontium is incorporated into bone mineralization via a similar mechanism to that related to calcium. In fact, also without being bound by theory, humans physiologically incorporate strontium into bone matrices altering the bone apatite. A primary feature reported was that Sr⁺2 was incorporated in bone matrices at a site normally occupied by calcium (Esteve, M. J., Farre, R., Frigola, A, Garcia-Cantabella, J. M. Determination of Ascorbic and Dehydroascorbic acids in Blood Plasma and Serum by Liquid Chromatography. Journal of Chromatography 688 (1997) 345-349). Epidemilogical studies suggest strontium plays a possible role in reducing dental caries (Curzon MEJ, (An association between strontium in drinking water supplies and low caries prevalence in man, Arch Oral Bio 23:317-321 (1978)). Investigations following moderate oral dosing of SrCl₂ indicated that strontium does not lower the serum and soft tissue levels of calcium (Skoryna, S. The Handbook of Stable Strontium, Plenum Press, New York, pp 11-617 (1966)). Additionally, it has also been shown that strontium stimulated bone formation in organ and cell cultures of rat calvariae (Vandecasteel, C., Vanhoe, H., and Dams, R., Determination of Strontium in Human Serum by Inductively Coupled Plasma Mass Spectrometry and Neutron Activation Analysis: A Comparison, Atlanta, 1990, (37): 8, 819-823). There have been a number of positive clinical results suggesting the relationship between strontium supplementation and bone health, particularly in relation to bone turnover at menopause (Vandecasteel, C., Vanhoe, H., and Dams, R. Determination of Strontium in Human Serum by Inductively Coupled Plasma Mass Spectrometry and Neutron Activation Analysis: A Comparison, Atlanta, 1990, (37): 8, 819-823). See also US Pub. No. 2006/0122274 A1 to Hansen et al. published Jun. 8, 2006, entitled “WATER-SOLUBLE STRONTIUM SALTS FOR USE IN TREATMENT OF CARTILAGE AND/OR BONE CONDITIONS” as well as the following references:

-   Meunier, P. J., et. al. Strontium Renelate: Dose-Dependant Effects     in Established Postmenopausal Vertebral Osteoporosis—A 2-Year     Randomized Placebo Controlled Trial. The Journal of Clinical     Endocrinology & Metabolism 2002, 87(5):2060-2066; and -   Anderson, R I, 1981 Ascorbic acid and Immune Functions: Mechanism of     Immunostimulation in Vitamin C (Ascorbic acid) by Counsell, J. M.     and Hornig, S. H. 249-272, New jersey, Applied Science Publishers.

SUMMARY

One or more aspects and/or advantages will be set forth, in part, in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.

According to an embodiment, the compound of formula (1) is:

(ascorbate)₂Sr:(M^(+a))_(x)(ascorbate)_(y)

wherein ascorbate refers to the ascorbate anion:

where y is a positive integer, where x is a positive integer, where a is a positive integer reflecting the valence of M; where (y)=((x) multiplied by (+a)) such that a total positive charge ((x) multiplied by (+a)) equals a total negative charge (y) provided that the ascorbate anion has a negative valence of (−1); and where M is an alkali metal, an alkali earth metal or Mn, Cu, Zn, Fe and a combination thereof. M may also be Na, K, Mg, Ca and combinations thereof.

According to an embodiment, a method for making the compounds of formulas (1), (2) and/or (2-a) described herein may include the following steps conducted in any order sufficient to yield the desired product:

-   -   (a) dissolving at least a stoichiometric amount of ascorbic acid         in water at a first solution temperature sufficient to dissolve         the ascorbic acid in a solution;     -   (b) adding at least a stoichiometric amount of strontium         carbonate (SrCO₃) to the solution of ascorbic acid;

Exclusion Criteria:

-   -   Subjects who are sensitive to any of the ingredients in the test         articles.     -   Subjects taking routine high dosage anti-inflammatory         medications (aspirin, ibuprofen).     -   Subjects who cannot comply with the dietary requirements.     -   Any condition for which the Investigator determines that the         subject could be placed under undue risk.

Samples:

Ascorbic acid samples were prepared in the following formulations:

-   -   1. 500 mg Ascorbic acid in a pink colored gelatin capsule.     -   2. 500 mg Ascorbic acid from (Magnesium, Zinc, Calcium,         ascorbates) in a pink colored gelatin capsule     -   3. 500 mg placebo (cellulose) in a pink colored gelatin capsule.

Dosing/Sampling:

On the day of dosing each volunteer will consume 2 capsules of an ascorbic acid formulation or placebo. Blood will be drawn right before dosing and then 2, 4, 6, and 8 hours after dosing. The blood plasma will be separated by centrifugation and then split for mineral (when present) and Ascorbic acid testing. A 10% (by volume) metaphosphoric acid is added to the ascorbic acid test samples. Categories of drugs that can diminish the body's supply of vitamin C include: oral contraceptives (birth control pills), NSAIDs (non-steroidal anti-inflammatory drugs including aspirin), corticosteroids (like cortisone), sulfa drugs (often used as antibiotics or in cancer treatment), and barbituates. Results are illustrated in FIGS. 2A and 2B.

All patents, patent applications, all publications, and all references cited herein are incorporated herein by reference in their entirety for all purposes.

Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

-   -   (c) adding at least a stoichiometric amount of M carbonate         (M^(+a))_(x1)(CO₃)_(y1) to the solution having a second solution         temperature, where (+a)×(x1)=(−2)×(y1), where x1 is an integer         and y1 is an integer;     -   (d) adjusting the second solution temperature within a range         from about 40° C. to about 80° C. for a time sufficient to form         the compound of formula (1); and     -   (e) optionally, drying the slurry at a drying temperature and         for a drying time sufficient to yield at least the compound of         formula (1) in solid or semi-solid form.

According to yet another embodiment, optionally, calcium threonate may be added to the solution before step (d), before step (c) or before step (b). Alternatively, the calcium threonate may be added at any point of the above-noted method so long as such addition does not interfere (or substantially interfere) with the formation of the desired product. The desired product may be the compound of formulas (1), (2) and/or (2-a) in a desired purity.

According to a further embodiment, the compound of formulas (1), (2) and/or (2-a) may be provided in an oral dosage form together with a pharmaceutically acceptable excipient.

According to a further embodiment, the compound of formulas (1), (2) and/or (3) may be administered to a subject in need thereof or to a subject desiring to supplement the diet with the same. The subject may be a human or an animal.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more aspects and/or advantages will become apparent and more readily appreciated from the following description of one or more embodiments, when taken in conjunction with the accompanying drawings of which:

FIG. 1 depicts a theoretical structure of strontium calcium ascorbate.

FIG. 2A is a plot of plasma ascorbic acid concentration versus time for control (placebo), ascorbic acid, and strontium calcium ascorbate.

FIG. 2B is a plot of plasma strontium concentration versus time for control (placebo), and strontium calcium ascorbate.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Reference will now be made in detail to one or more embodiments.

Generically, the compound(s) of interest in connection with this disclosure are encompassed by the following general formula (1):

(ascorbate)₂Sr:(M^(+a))_(x)(ascorbate)_(y)

wherein ascorbate refers to the ascorbate anion (or equivalents thereof including all its tautometric forms):

which in its ascorbic acid form is depicted as:

wherein y=(x) multiplied by (+a) so that the total charge ((x) multiplied by (+a)) equals (y) being that the ascorbate anion has a single negative valence of (−1);

wherein y is a positive integer (e.g., 1, 2, 3, 4, 5, 6 or more), x is a positive integer (1, 2, 3, 4, 5, 6 or more) and a is a positive integer (e.g., 1, 2, 3, 4, 5, 6 or more) reflecting the valence of M; and

wherein M is an alkali metal (e.g., Na or K or a combination thereof) or an alkali earth metal (e.g., Mg or Ca or a combination thereof) or Mn, Cu, Zn, Fe and/or a combination thereof.

According to an embodiment, a compound of interest is that of formula (2):

(ascorbate)₂Sr:Ca(ascorbate)₂

having (without being bound by theory) the theoretical structure depicted as formula (2-a):

The process for making the compound of formula (2) includes the following steps:

-   -   (a) dissolving at least a stoichiometric amount of ascorbic acid         in water (e.g. distilled water) at a temperature sufficient to         dissolve the ascorbic acid (e.g., dissolve in distilled water at         90° C. (or at about 90° C. such as 87.7° C.) in an appropriate         reaction vessel such as a Mueller reaction vessel);     -   (b) adding at least a stoichiometric amount of strontium         carbonate (SrCO₃) to the above-noted solution of ascorbic acid         (e.g., preferably slowly adding the strontium carbonate in         powder form);     -   (c) adding at least a stoichiometric amount of calcium carbonate         (CaCO₃) to the above noted reaction vessel (e.g., preferably         slowly adding the calcium carbonate in powder form)—noting that         the stoichiometric amount in moles of Sr and moles of Ca will         depend upon the ratio of moles of Sr to the moles of Ca used, so         that the total stoichiometric amount in moles of ascorbate will         be at least twice the number of (moles of Sr+moles of Ca)—to         form a slurry;     -   (d) adjusting the slurry temperature in a range from about         40° C. to about 80° C. (e.g., 40-80° C., from about 45° C. to         about 75° C., 45-75° C., from about 50° C. to about 70° C.,         50-70° C., from about 55° C. to about 65° C., 55-65° C., from         about 58° C. to about 62° C., 58-62° C., from about 59° C. to         about 60° C., or 59-60° C.) for a time (e.g., 10 minutes, 20         minutes, 30 minutes, 40 minutes, 50 minutes, 1 hour, 2 hours, or         increments thereof as needed depending on the size of the batch         of slurry) sufficient to form the compound of formula (2); and     -   (e) drying the slurry at a drying temperature (e.g., about         120° F. which is about 50° C.) and for a drying time sufficient         to yield at least the compound of formula (2) in solid form         (e.g, powder, cake, and/or other suitable form etc.).

According to another embodiment, the compound of formula (1) may be formed according to the above-noted process except that instead of (CaCO₃) either (M^(+a′))_(x′)(CO₃)_(y′) where (x′) multiplied by (+a′)=(y′) or (M^(+a′))_(x′)(anion^(−b))_(y′), where (x′) multiplied by (+a′)=(−b) multiplied by (y′) may be used. Note that (+a′) is a positive integer (e.g, 1, 2, 3, 4, 5, 6 or more) and reflects the valence of the metal (M), that (−b) is a negative integer (e.g, −1, −2, −3, −4, −5, −6 or less) and reflects the valence of the anion (e.g., chloride, carbonate, etc.). According to yet another embodiment, optionally, calcium threonate may be added to the solution before step (d), before step (c) or before step (b). Alternatively, the calcium threonate may be added at any point of the above-noted method so long as such addition does not interfere (or substantially interfere) with the formation of the desired product. The desired product may be the compound of formulas (1), (2) and/or (2-a) in a desired purity (e.g., 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9% or better, respectively).

According to a further embodiment, the compound of formulas (1), (2) and/or (2-a) may be provided in an oral dosage form together with a pharmaceutically acceptable excipient. See Remington's Pharmaceutical Sciences, 16^(th) Edition, A. Osol, Ed., Mack Publishing Co., Easton, Pa. (1980) and all later editions of the same. The composition may be an oral dosage form selected from the group consisting of a tablet, a capsule, a softgel capsule, a liquid, a syrup, a suspension, a sublingual tablet, a powder, and a lozenge. The oral dosage form may be an immediate release dosage form or an extended release dosage form.

Moreover, in step (a) any solvent other than water may be used that is suitable for forming the desired product of formulas (1), (2) and/or (2-a). Thus, for example, ethanol may be used instead of water with the proper temperature and time adjustments to those recited in steps (c), (d) and/or (e) as would be well within the knowledge of one of ordinary skill in the art in conjunction with this disclosure. Also, the above noted temperatures refer to temperatures at 1 atm pressure. However, if lower or higher pressures are used, then the temperatures and times in steps (c), (d) and/or (e) may be appropriately raised or lowered as would be well within the knowledge of one of ordinary skill in the art in conjunction with this disclosure.

According to another embodiment, appropriate stoichiometric amounts of the moles of Sr salts and/or Ca salts may be used to yield the compound of formula (2) wherein the ratio of the moles of Sr to the moles of Ca may be any one of the following, including but not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.25, 2.5, 2.75, 3, or 4. Also the amount of water or other solvent to form the slurry may be adjusted as needed to achieve the appropriate ratio ranging from 0.1 to 4 and the heating, temperature and pressure conditions may be adjusted accordingly to yield the desired product. Further, the stoichiometric amount of ascorbate, ascorbate salt, and/or ascorbic acid used may be adjusted to provide that amount at least needed to react with the Sr salts and/or Ca salts used according to the above-noted process and description provided herein.

According to another embodiment, appropriate stoichiometric amounts of the moles of Sr salts and/or M salts may be used to yield the compound of formula (1) wherein the ratio of the moles of Sr to the moles of M may be any one of the following, including but not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.25, 2.5, 2.75, 3, or 4. Also the amount of water or other solvent to form the slurry may be adjusted as needed to achieve the appropriate ratio ranging from 0.1 to 4 and the heating, temperature and pressure conditions may be adjusted accordingly to yield the desired product. Further, the stoichiometric amount of ascorbate, ascorbate salt, and/or ascorbic acid used may be adjusted to provide that amount at least needed to reach with the Sr salts and/or M salts used according to the above-noted process and description provided herein.

The water used may be distilled water, deionized water or any other form of water that does not interfere (or does not substantially interfere) with the synthetic steps necessary to form the desired product e.g., compounds of formulas (1), (2) and/or (2-a).

According to yet another embodiment, between steps (c) and (d), optionally, calcium threonate may be added to the slurry such that the amount of calcium threonate added is from about 1% to about 5% by weight of the final total weight of the desired product (including the weight of the calcium threonate) of formulas (1), (2) and/or (2-a) in dry form.

According to an embodiment, a suitable manufacturing method for the compounds include using a pure form of L-ascorbic acid, strontium carbonate and any one of the other metal carbonates (or other suitable salts) of calcium, magnesium, manganese, zinc, copper, sodium, potassium, and iron. For example, the vitamin C (ascorbic acid) is dissolved in water and heated to between 60-100° C. To convert the vitamin C into the corresponding salt, the strontium and other mineral carbonates are added in at least the stoichiometrically needed amounts to yield the compounds of formulas (1), (2) and/or (2-a).

Using the methodology described herein, the resulting compounds of formulas (2) and/or (2-a) match the standardized Fourier Transformed Infrared Spectroscopy (FTIR) scan with a high correlation. Also, the compounds of formulas (2) and/or (2-a) so made have an ascorbic acid value that ranges from 705-770 mg/g assayed by High Performance Liquid Chromatography (HPLC), a strontium value of 100-130 mg/g assayed by Inductively Coupled Plasma Optical Emissions Spectroscopy (ICP-OES), and the remaining mineral component has a value of 30-50 mg/g assayed by ICP-OES. The ranges of all three components may change because of the varying molecular weights and formulated ratios. However, the overall stoichiometry are two moles of vitamin C to one mole of a divalent mineral e.g. strontium, M, Ca, etc.

The analytical procedures utilized are described in: Clinical Chemistry, Principles and Techniques, edited by Richard J. Henry, Donald D. Cannon and James W. Windelman, Harper and Row, 1974 p. 1393-1398.

Below are provided non-limiting examples of certain aspects of the invention.

Example 1 Strontium ascorbate (M) salt Manufacturing Process

The following reaction is carried out to form a strontium (M) ascorbate salt using ascorbate, strontium and calcium where the Sr:Ca mole ratio is 0.6 moles Sr:0.4 moles Ca. Ascorbic acid is dissolved in distilled H₂O at 90° C. in an appropriate reaction vessel (Meuller). The water mass is 10-25% of the mass of ascorbic acid. As soon as the ascorbic acid is dissolved, slowly add strontium carbonate followed by calcium carbonate. Keep temperature constant. As the reaction proceeds, add 0.5-5% water by mass. Reduce temperature to 60° C. 10 minutes after the last of the mineral salt is added. The resulting slurry is transferred to trays and placed in the oven at 60° C. until dry. Optionally, the strontium ascorbate (M) salt may need to be turned over once as part of the drying process. The dry strontium ascorbate (M) salt mass can be milled to varying particle sizes including a fine powder or a granular powder for use in various oral dosage forms.

Example 1a Alternate Strontium Calcium Ascorbate Salt Manufacturing Process

Carry out the following steps in the order listed below (can vary order to get same product):

-   -   (1) Heat 6 gallons of water to 190° F.;     -   (2) Add 36.364 kg of ascorbic acid (e.g., powder or other         readily water dissolvable form) to the heated water;     -   (3) Add another gallon of water (preferably at about 190° F. or         other suitable temperature);     -   (4) Permit all (or nearly all) the ascorbic acid to dissolve         (requires about 10 min with stirring if necessary);     -   (5) Slowly add 9.116 kg of strontium carbonate (e.g., powder or         other readily water dissolvable form) to the ascorbic acid         solution;     -   (6) Slowly add 4.02 kg of calcium carbonate (e.g., powder or         other readily water dissolvable form);     -   (7) Reduce temperature of reaction mixture (e.g., reactants         added to the water and the water itself) to about 150° F.;     -   (8) Stir the reaction mixture from about 20 to about 30 minutes         and monitor reaction mixture visually for color and         viscosity—until, for example, see a light/yellow brown color         being formed and slurry formation.     -   (9) After about 15-20 minutes, slowly add 500 grams of calcium         L-threonate to reaction mixture and stir for another 5-10         minutes;     -   (10) Place reaction mixture (e.g., slurry) onto dry racks and         dry (e.g., in an oven) at about 120° F. until dry (or suitably         dry); and     -   (11) Optionally, test sample/batch formed.

The foregoing salt made in this manner may be combined with other ingredients to form the formulation noted below in capsule form with each capsule (e.g., gelatin capsule, vegetable cellulose capsule, or other orally acceptable capsule suitable for human consumption) containing:

1 -- Ingredients per capsule Strontium calcium ascorbate 500 mg Bioflavinoid concentrate 200 mg Optional Ingredients (1 or more of) Heperidin concentrate Rutin concentrate Acerola cherry Indole-3 carbinol  25 mg (Vitamin c support base) Silica Calcium-L-threonate 2 -- Ingredients per capsule Strontium calcium ascorbate 500 mg Optional Ingredients (1 or more of) Bioflavinoid concentrate 200 mg Heperidin concentrate Rutin concentrate Acerola cherry Indole-3 carbinol  25 mg (Vitamin c support base) Silica Calcium-L-threonate

This application includes the product(s) made by the process(es) described herein. The pH of the product(s) formed according to the process(es) described herein may be adjusted as suitable for human (e.g., oral) consumption (e.g., about pH 7-8 including about or exactly pH 7.1, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, or 8.0, respectively) with pharmaceutically acceptable pH adjusting ingredients in the appropriate quantities.

Example 2 Testing and Qualification of the Final Powder Includes Sensory (Color, Taste, Appearance), pH, FTIR, HPLC, ICP-OES and ICP-MS

Analytical Testing:

An FTIR method was developed to follow the reaction between the ascorbic acid and the mineral carbonates. Samples at various time points following addition of the mineral carbonates to the dissolved ascorbic acid were collected at time zero, 1 minute, 5 minutes, 10 minutes, 15 minutes, 30 minutes and 60 minutes and scanned using FTIR. The change in spectra was monitored and used to determine optimal reaction periods. Specifically, changes in the carbonyl, and carboxyl group peaks were followed.

The HPLC method was developed from Esteve, M. J., et. al., cited herein with modifications. Prior to the actual bioavailability analysis blood samples were drawn and spiked with known concentrations of ascorbic acid. Separation, accuracy, precision and limit of detection were estimated based on multiple injections of standards and spiked samples.

The ICP method was developed from Vandecasteel, C., et. al., cited herein with modifications. Prior to the actual bioavailability, analysis blood samples were drawn and spiked with known concentrations of strontium. Accuracy, precision and limit of detection were estimated based on multiple injections of standards and spiked samples.

Example 3 Bioavailability Study

Blood samples are drawn into vacu-tubes containing heparin. These tubes are then centrifuged at 6000 rpm for 15 minutes. The serum was pulled from the top and aliquots are placed in HPLC vials or ICP-MS vials. The sample preparation and analysis takes place immediately following the blood drawn.

HPLC Sample Prep:

Reducing vial contents are 100 μl of 0.01 M DDT, 300 μl serum, 200 μl distilled H₂O and 600 μl 10% (by volume) metaphosphoric acid. Non-reducing vial contents are 300 μl serum, 300 μl distilled H₂O and 600 μl 10% (by volume) metaphosphoric acid. Ascorbic acid purchased from Sigma Aldrich was weighed into 100 ml distilled H₂O/10% by volume metaphosphoric acid sufficient to provide serial dilutions ranging from 100 μg/ml to 4 μg/ml.

ICP Sample Prep:

Approximately 100 mg of serum was weighed into 100 ml volumetric flask. The samples were diluted with 80 ml distilled H₂O, spiked with 10 ppb yttrium (Y) as an internal standard and diluted to volume with distilled water. The strontium content was determined at mass 88 and quantified against a 4 point standard curve, ranging from 0 to 10 ppb.

Study Protocol

Participants:

Eight health adults, 7 men and 1 woman, were recruited for the study. There ages ranged from 22 to 37. None of the participants were smokers currently; however, one of the men had been a smoker. They all consumed a healthy diet, and most of them regularly took vitamin and mineral supplements.

All participants were asked to refrain from taking nutritional supplements and eating foods high in ascorbic acid two days prior to each dosing. On the day of the dosing and plasma sampling, the participants did not consume any food until the last sample was taken.

Inclusion Criteria:

-   -   Subject and/or legal guardian of the subject willing to sign an         Informed Consent Form, Assent Form if indicated, and a HIPAA         Authorization Form.     -   Male and female subjects between the ages of 18 and 45 years and         in generally good health.     -   Subjects who have not used dietary supplements or medications         for 48 hours prior to start of study.     -   Subjects who agree not to use supplements or medicines that         would interfere with vitamin C during the study.     -   Subjects who exhibit dependability and intelligence in following         directions. 

1-19. (canceled)
 20. A method of making the compound of formula (1): (ascorbate)₂Sr:(M^(+a))_(x)(ascorbate)_(y) wherein ascorbate refers to the ascorbate anion:

wherein y is a positive integer, wherein x is a positive integer, wherein a is a positive integer reflecting the valence of M; wherein (y)=((x) multiplied by (+a)) such that a total positive charge ((x) multiplied by (+a)) equals a total negative charge (y) provided that the ascorbate anion has a negative valence of (−1); and wherein M is an alkali metal, an alkali earth metal or Mn, Cu, Zn, Fe and a combination thereof, the method comprising: (a) dissolving at least a stoichiometric amount of ascorbic acid in water at a first solution temperature sufficient to dissolve the ascorbic acid in a solution; (b) adding at least a stoichiometric amount of strontium carbonate (SrCO₃) to the solution of ascorbic acid; (c) adding at least a stoichiometric amount of M carbonate (M^(+a))_(x1)(CO₃)_(y1) to the solution having a second solution temperature, where (+a)×(x1)=(−2)×(y1), where x1 is an integer and y1 is an integer; (d) adjusting the second solution temperature within a range from about 40° C. to about 80° C. for a time sufficient to form the compound of formula (1); and (e) optionally, drying the slurry at a drying temperature and for a drying time sufficient to yield at least the compound of formula (1) in solid or semi-solid form. wherein the strontium carbonate (SrCO₃) is provided in powder or granular form.
 21. The method of claim 20 wherein step (c) comprises incrementally adding the M carbonate (M^(+a))_(x1)(CO₃)_(y1) to the solution.
 22. The method of claim 21, wherein the M carbonate (M^(+a))_(x1)(CO₃)_(y1) is calcium carbonate (CaCO₃).
 23. The method of claim 22, wherein the calcium carbonate (CaCO₃) is provided in powder or granular form.
 24. The method of claim 20, wherein the ratio of the moles of Sr to the moles of M is selected from the group consisting of, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.25, 2.5, 2.75, 3, and
 4. 25. The method of claim 24 wherein the compound of formula (1) is the compound of formula (2): (ascorbate)₂Sr:Ca(ascorbate)₂ wherein Sr refers to strontium and Ca refers to calcium.
 26. The method of claim 24 wherein the moles of Sr plus the moles of M is at least twice the moles of ascorbic acid dissolved in the solution.
 27. The method of claim 26 wherein M is selected from the group consisting of Na, K, Mg, Ca, Mn, Cu, Zn, Fe and combinations thereof.
 28. The method of claim 27 wherein the second solution temperature is maintained within a temperature range selected from the group consisting of (1) from about 45° C. to about 75° C., (2) from about 50° C. to about 70° C., (3) from about 55° C. to about 65° C., (4) from about 58° C. to about 62° C., (5) from about 59° C. to about 60° C., and (6) about 60° C.
 29. The method of claim 20 further comprising (f) adding calcium threonate to the solution before step (d), before step (c), or before step (b) after in an amount such that the amount of calcium threonate added is from about 1% to about 5% by weight based on a final total weight of the compound (including the weight of the calcium threonate) of formula (1) in dry form.
 30. The method of claim 29, wherein the compound of formula (1) is the compound of formula (2) of claim
 25. 31. The method of claim 20 wherein the compound of formula (1) is in a solid form.
 32. The method of claim 30, wherein the compound of formula (2) is in a solid form.
 33. The method of claim 31, wherein the solid form is a powder form, a granular form, or a cake form.
 34. The method of claim 32, wherein the solid form is a powder form, a granular form, or a cake form.
 35. (canceled)
 36. The method of claim 20, wherein M is Na or K.
 37. The method of claim 20, wherein M is Na.
 38. The method of claim 20, wherein M is Mg, or Ca.
 39. The method of claim 20, wherein M is Mn, Cu, Zn, or Fe.
 40. The method of claim 20, wherein M is Fe. 